Nitride compound semiconductors are frequently used in LEDs or laser diodes which generally emit in the blue spectral range. Depending on the composition of the semiconductor material, e.g., emission in the ultraviolet or green spectral range is also possible. By reason of luminescence conversion by luminescent substances, shortwave radiation can be converted to longer wavelengths. In this manner, it is possible to produce mixed-colored light, in particular white light. Therefore, LEDs based upon nitride compound semiconductors are of considerable importance for LED illumination systems.
During the production of optoelectronic components, the nitride compound semiconductor layers are generally epitaxially grown onto a growth substrate which is adapted to the lattice constant and the crystal structure of the nitride compound semiconductor material. Suitable substrate materials are in particular sapphire, GaN or SiC. However, these substrate materials are comparatively expensive.
Growth of nitride compound semiconductors on comparatively inexpensive silicon substrates is hindered by a comparatively large difference in the coefficients of thermal expansion of the silicon and the nitride compound semiconductor material. In particular, when the layer system is cooled from the growth temperature of about 1000° C., which is used for the growth of nitride compound semiconductors, to room temperature large tensile stresses are produced in the GaN.
DE 10 2006 008 929 A1 and WO 2011/039181 A1 each describe methods of producing nitride compound semiconductor components on silicon substrates. Those publications incorporate a layer structure between the silicon surface of the growth substrate and the functional layer sequence of the optoelectronic component to produce a compressive stress which counteracts the tensile stress produced by the silicon during cooling.
It could nonetheless be helpful to provide a further improved method of producing an optoelectronic nitride compound semiconductor component on a substrate having a silicon surface by which particularly small defect densities can be attained in the functional semiconductor layer sequence to achieve particularly high levels of efficiency.